Fuel-burning means for a gaseous fluid propulsion jet



April 1955 s. ALLEN 2,705,400

FUEL BURNING MEANS FOR A GASEOUS FLUID PROPULSION JET Filed Dec. 5, 1952 2 Sheets-Sheet i Ill/MENTOR W 3/17/11, ALLEN April 5, 1955 s. ALLEN 2,705,400

FUEL BURNING MEANS FOR A GASEOUS FLUID PROPULSION JET Filed Dec. 5, 1952 2 Sheets-Sheet 2 IIVI/EXVTOB H63 SID/VEV ALLEN .xs/ Z 27 at 197778.

United States Patent FUEL-BURNING MEANS FOR A GASEOUS FLUID PROPULSION JET Sidney Allen, Coventry, England, assignor to Armstrong Siddeley Motors Limited, Coventry, England Application December 5, 1952, Serial No. 324,259

Claims priority, application Great Britain January 31, 1952 6 Claims. (Cl. 60-39.71)

This invention relates to a fuel-burning means in a jet pipe of a turbo-jet or ram-jet engine, of the kind having a flame stabiliser supported in the jet pipe and serving to stabilise an initial flame for igniting the main supply of fuel, thus to ensure that the main supply will be usefully burnt.

One very satisfactory form of stabiliser consists of an axially-disposed casing, upstream of the combustion zone and diverging downstream, having, at the upstream end of the casing, swirl-introducing vanes through which can pass, to the interior of the casing, sutficient gaseous fluid from the jet pipe for the combustion of a pilot supply of fuel to provide the initial flame, the pilot supply being provided in the interior of the casing with an igniter.

There are also other forms of flame stabiliser.

In all such cases the igniter for the pilot supply of fuel, to provide the initial flame, is in the form of a sparking plug. In some cases the sparking plug extends from the exterior of the jet pipe into the interior of the stabiliser casing. The provision of an adequate form of such sparking plug, however, involves difliculties; and it is the main object of the present invention to avoid this disadvantage in a simple manner.

According to the invention, ignition means, in or near the wall of the jet pipe, is disposed in a duct in association with an ignition supply of fuel to the duct, and a supply of gaseous fluid from the jet pipe is also delivered to the duct, near the ignition means, to institute an ignition flame which is carried by the duct to the interior of the stabiliser at a desirable point. The said duct may be provided by one of the stabiliser supporting webs, when the stabiliser is supported by webs from the jet pipe.

There may be a pilot supply of fuel to the stabiliser, to be ignited by said ignition flame. Alternatively, the pilot supply may be solely used as the said ignition supply-- i. e., the said ignition flame to serve as the said initial flame.

In the accompanying drawings:

Figure 1 is a cross section of a jet pipe having in it a flame stabiliser, provided with a hollow supporting web which forms a duct as aforesaid supplying the stabiliser with an ignition flame;

Figure 2 is an enlarged section of the hollow web, taken on the line 2-2 of Figure 1;

Figure 3 is a view corresponding to that of Figure 2 but showing a modification of the invention; and

Figure 4 is a cross-section taken on the line 4-4 of Figure 3, Figure 5 being an enlarged fragmentary view of another modification.

In the construction shown by Figures 1 and 2 the stabiliser 11 is supported by three struts or webs 13, 14 and 15 from the wall of the jet pipe by means of screws 17 engaged in screw threaded holes in bosses 18 at the closed outer ends of the webs. As will be seen from Figure 2 particularly, the stabiliser consists of a casing which is divergent downstream and has a closed upstream end 19 surrounded by a ring of swirl-introducing vanes 20. The ignition means is in the form of a sparking plug 22 which extends through the jet pipe just into the interior of one of the webs 13, and is there associated with some form of ignition fuel sprayer, indicated at 23. Obviously, if desired, the sparking plug and fuel sprayer may be replaced by what is commonly termed a torch igniter, this combining the functions of the two.

Gaseous fluid (air in the case of a ram-jet engine) is taken to the ignition means from the interior of the jet 2,705,400 Patented Apr. 5, 1955 pipe as by means of a hole 24 provided for the purpose in the leading edge of the web 13, or through two or more holes, at the radially outer end of the web. The web may be entirely hollow as shown, the stabiliser casing having an opening 26 at an appropriate place through which the ignition flame (of the ignition supply of fuel 23 and the gaseous fluid taken to the ignition means 22) is led to the interior of the stabiliser casing to initiate the said initial flame in the latter.

If desired an appropriate baflie 28 may be disposed partly between the said hole 24 or holes in the web and the ignition means 22 with a view to causing turbulance of the gaseous fluid taken to the ignition means, whereby to assist the formation of the ignition flame.

With such an arrangement the sparking plug 22 or torch igniter is disposed in a relatively cool position and may thus have a long life, whilst the choice of the ignition means is not so restricted as in the case when the igniter extends into the interior of the stabiliser casing.

As previously mentioned, the pilot supply of fuel may be that of the ignition supply, delivered by the sprayer 23. Alternatively, there may be a definite pilot supply directed to the stabiliser casing which is independent of the ignition supply 23, Figure 1 showing such a supply line 30 disposed within the web 14.

Furthermore, whereas the web 13 is shown in Figure 2 as communicating with the stabiliser casing through a plain opening 26, an alternative method of supplying the ignition flame to the stabiliser casing is shown by Figures 3 and 4, in which, instead of the opening 26, use is made of a short tube 32 which carries the ignition flame to the quieter region of the staliser behind the closed end 19 thereof.

The modification shown in Figures 3 and 4 (in which certain parts which are similar to those of Figures 1 and 2 are given the same reference numerals) differs mainly in that the ignition supply of fuel (23 in Figure 2) is delivered along a pipe 34 to a vaporising-means here shown as an L-like pipe 36 disposed in the interior of the web 13 with its shorter limb 37 terminating adjacent the ignition means 22, the longer limb extending upstream and through the wall of the web so as to take in the requisite quantity of gaseous fluid for combustion from the jet pipe. As will be well understood, the fuel delivered along the pipe 34 will in consequence be vaporised and ready for ignition by the ignition means 22 when issuing from the outlet end of the L-like pipe.

In Figures 3 and 4 it is assumed that the L-like pipe is of suflicient bore to take in all the gaseous fluid which is necessary for the combustion of the fuel delivered along the pipe 34. If preferred, however, as shown by Figure 5, the L-like pipe 36 may be of less diameter so as to take in only some of the air necessary for combustion, and arranged alongside it are two similar L-like pipes 39, one on each side of the pipe 36 into which the fuel from the pipe 34 is delivered, by means of which additional gaseous fluid is delivered adjacent the ignition means 22 to support combustion.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A fuel-burning means for a jet pipe of a jet engine, including a main supply of fuel, a flame stabiliser supported in the jet pipe and serving to stabilise an initial flame for igniting said main supply of fuel, means providing a duct leading from near the wall of the jet pipe to the interior of the stabiliser, ignition means disposed in the duct near the wall of the jet pipe, means providing an ignition supply of fuel to the duct associated with said ignition means, and means for delivering gaseous fluid from the jet pipe to the duct near said ignition means to institute an ignition flame which is carried by the duct to itihe interior of the stabiliser to serve therein as said initial ame.

2. A fuel-burning means for a jet pipe of a jet engine, including a main supply of fuel, a flame stabiliser serving to stabilise an initial flame for igniting said main supply of fuel, the stabiliser being supported in the jet pipe by webs, one of said webs being hollow and providing a duct leading from the wall of the jet pipe to the interior of the stabiliser, ignition means: extending through the wall of the jet pipe into the outer end of said one web,

an ignition supply of fuel to said ignition means, and means for delivering gaseous fluid from the jet pipe to the interior of'said one web near said ignition means to institute an ignition flame which is carried by the duct to the interior of the stabiliser to serve therein as said initial flame.

3. A fuel-burning means for a jet pipe of a jet engine, including a main supply of fuel, a flame stabiliser supported in the jet pipe and serving to stabilise an initial flame for igniting said main supply of fuel, means pro viding a duct leading from near the wall of the jet pipe to the interior of the stabiliser, ignition means disposed in the duct near the wall of the jet pipe, and means providing an ignition supply of fuel to the duct associated with said ignition means, and means providing the duct having a hole in its leading edge near the radially-outer end thereof by which gaseous fluid is delivered from the jet pipe to the duct near said ignition means to institute an ignition flame which is carried by the duct to the interior of the stabiliser to serve therein as said initial flame.

4. A fuel-burning means, according to claim 3, and including a baffle in the duct disposed partly between said hole and the ignition means.

5. A fuel-burning means for a jet pipe of a jet engine,

said one web associated with 4 including a main supply of fuel, a flame stabiliser supported in the jet pipe and serving to stabilise an initial flame for igniting said'main supply of fuel, means providing a duct leading fromnear the wall of the jet pipe to the interior of the stabiliser, ignition means disposed in the duct near the wall of the jet pipe, an ignition supply of fuel, and vaporizing means for said ignition supply of fuel and a supply of gaseous fluid from the jet .pipe to the duct near said ignition means to institute an ignition flame which is carried by the duct to the interior of the stabiliser to serve therein as said initial flame.

' 6. A fuel-burning means, according to claim 5, characterised in that said vaporising means includes an L-like pipe-with its shorter limb terminating in the duct near said ignition means, and with its longer limb extending through. the leading edge of the means providing the duct, said ignition supply of fuel being delivered into the upstream end of said longer limb.

References Cited in the file of this patent UNITED STATES PATENTS 2,622,396 Clarke et a1. Dec. 23, 1952 2,635,426 Meschino Apr. 21, 1953 

1. A FUEL-BURNING MEANS FOR A JET PIPE OF A JET ENGINE, INCLUDING A MAIN SUPPLY OF FUEL, A FLAME STABILISER SUPPORTED IN THE JET PIPE AND SERVING TO STABILISE AN INITIAL FLAME FOR IGNITING SAID MAIN SUPPLY OF FUEL, MEANS PROVIDING A DUCT LEADING FROM NEAR THE WALL OF THE JET PIPE TO THE INTERIOR OF THE STABILISER, IGNITION MEANS DISPOSED IN THE DUCT NEAR THE WALL OF THE JET PIPE, MEANS PROVIDING AN IGNITION SUPPLY OF FUEL TO THE DUCT ASSOCIATED WITH SAID IGNITION MEANS, AND MEANS FOR DELIVERING GASEOUS FLUID FROM THE JET PIPE TO THE DUCT NEAR SAID IGNITION MEANS TO INSTITUTE AN IGNITION FLAME WHICH IS CARRIED BY THE DUCT TO FLAME. 